1. Field of the Invention
The present invention relates to a bulb socket having a watertight structure and to a method for mounting or assembling it.
2. Description of the Related Art
Japanese Unexamined Utility Model Publication No. 4-51784 and FIG. 5 herein disclose a known bulb socket. The letter B in FIG. 5 identifies the known bulb socket that has a bulb i mounted in a socket main body 2. A ring-shaped seal 3 is fitted on the outer side surface of the main body 2. The bulb socket B is mounted on a panel 4 so that the seal 3 is squeezed between a flange 2a of the main body 2 and an edge of a mount hole 5 in the panel 4. Thus, the seal 3 is pressed in sealing contact with the flange 2a and the edge of the mount hole 5. Locking pieces 2b are provided on the outer surface of the socket main body 2 and are introduced through escaping portions 5a formed at the edge of the mount hole 5. Thus, the entire bulb socket B is turned circumferentially while the seal 3 is pressed against the panel 4 by the flange 2a. As a result, the engagement of the locking pieces 2b with the edge of the mount hole 5 prevents the bulb socket B from coming out.
The bulb socket B may have to be detached from the panel 4, for example, to exchange the bulb 1. However, the seal 3 is held strongly in pressing contact with the edge of the mount hole 5 when the bulb socket B is mounted, and the seal 3 may remain held in pressing contact with the edge of the mount hole 5. Consequently, the seal 3 may come off the main body 2 as the bulb socket B is detached.
The seal 3 may be squeezed excessively between the flange 2a of the main body 2 and the edge of the mount hole 5, if the flange 2a of the main body 2 is pressed too hard against the edge of the mount hole 5 during the mounting of the bulb socket B. If the bulb socket B is turned circumferentially in this state, a sliding resistance between the seal 3 and the flange 2a and the resistance between the seal 3 and the mount hole 5 increases, and a shear force acts on the seal 3 in the circumferential direction. As a result, the seal 3 is deformed improperly and cannot provide a secure sealing.
The invention was developed in view of the above problem and an object thereof is to prevent a reduction in sealing function of a sealing member.
The invention relates to a bulb socket with a main body for receiving a bulb. The main body has an outer surface with at least one lock for locking the main body in a mount hole of a bulb casing. A seal is mounted on the outer surface of the main body to provide sealing between the mount hole and the main body. The outer surface of the main body includes a restricting projection between the seal and the mount hole for contacting the edge of the mount hole from the outside. The restricting projection limits the depth of insertion of the bulb socket in the mount hole and hence prevents excessive resilient deformation of the seal in response to forces generated as the bulb socket is being mounted. Thus, the seal is not deformed improperly even if the bulb socket is turned in this state, and the seal is assured of displaying its sealing function.
The main body preferably can be turned circumferentially to engage the lock with an edge of the mount hole from inside. Thus, the main body will not come out during mounting into the bulb casing.
The bulb socket preferably comprises a flange on the outer circumferential surface of the main body for contacting the seal and restricting a backward loose movement of the seal. Thus, sealing is provided between the mount hole and the main body by squeezing the seal between the flange and a sealing surface of the edge of the mount hole to resiliently deform the seal in a mounted state of the bulb socket.
The seal is held in pressing contact with the outer side of the edge of the mount hole. However, the restricting projection on the outer surface of the main body contacts the seal and separates the seal from the edge of the mount hole as the bulb socket is detached. Thus, the seal will not come off the main body as the bulb socket is detached.
The seal could be pushed strongly against the edge of the mount hole by the flange during the mounting of the bulb socket. However, the restricting projection contacts the outer side of the edge of the mount hole before the seal undergoes an excessive resilient deformation. Thus, the bulb socket cannot be pushed any deeper. The seal is not deformed improperly even if the bulb socket is turned in this state and, therefore, can display its sealing function.
The restricting projection preferably is formed substantially continuously over the entire circumferential surface of the main body. Accordingly, the strength against a pushing force from the edge of the mount hole when the bulb socket is pushed is higher than on a bulb socket with a plurality of circumferentially spaced restricting projections. Thus, breakage and bending of the restricting projection can be avoided. Further, oblique mounting of the socket main body into the mount hole can be avoided because the restricting projection uniformly contacts the edge of the mount hole over the entire circumference.
The restricting projection preferably is formed with a contact surface to be held in pressing contact with the seal when the seal is squeezed resiliently between the flange and the sealing surface. Accordingly, the seal is held in pressing contact with the edge of the mount hole, the flange of the socket main body, and the contact surface of the restricting projection. Thus, more secure sealing is provided between the mount hole and the socket main body.
The restricting projection preferably is formed with a slanted surface that extends substantially along the outer circumferential surface of the seal. Accordingly, the seal contacts a wide area, i.e. substantially the entire slanted surface, when pressed against the restricting projection. Thus, the seal will not be recessed locally.
A groove may be formed in the outer circumferential surface of the main body for at least partly accommodating the seal.
The invention also is directed to a method for mounting a bulb socket. The method comprises providing a main body with a restricting projection and a lock on an outer circumferential surface of the main body. The method then comprises fitting a seal on the outer circumferential surface of the main body and inserting the main body into a mount hole of a bulb casing so that the restricting projection contacts and edge of the mount hole from the outside. The contact between the restricting projection and the outer side of the edge of the mount hole prevents the seal from undergoing an excessive resilient deformation even if strong pushing forces are used during the mounting of the bulb socket. Thus, the seal provides reliable sealing between the mount hole and the main body.
The method may further comprise locking the main body to the bulb casing preferably by circumferentially turning the main body to engage a lock with an edge of the mount hole from inside. Thus, the main body will not come out during the mounting into the bulb casing.
These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments.